Impulse repeating arrangement for telephone or like systems



March 18, 1941. w, V PER 2,235,343

IMPULSE REPEATING ARRANGEMENT FOR TELEPHONE 0R LIKE SYSTEMS Filed Feb. 9, 1938 2 Sheets- Sheet 1 INVENTOR WILL/AM TYLER VOSPER I ATTY.

March 18, 1941. w T, VO PER 2,235,343

IMPULSE REPEATING ARRANGEMENT FOR TELEPHONE 0R LIKE SYSTEMS Filed Feb. 9, 1938 2 Sheets-Sheet 2 INVENTOR /LL/AM TYLER VOSPEP ATTY Patented Mar. 18, 1941 IMPULSE REPEATING ARRANGEMENT FOR TELEPHONE OR LIKE SYSTEMS William Tyler Vesper, New Eltham, London, England, assignor. to Siemens Brothers & Company Limited, London, England v Application February 9, 1938, Serial No. 189,517 In Great Britain February 26, 1937 9 Claims. (01. 179-16) This invention relates to automatic telephone and like selective systems and is concerned more particularly with improved arrangements for the repetition of dialled or similar impulses in such systems. The arrangements contemplated are of the kind in which provision is made to ensure as far as possible that the repeated impulses have make and break periods of lengthswhich are not less than the minimum required for satisfactory impulsing even thoughthe received impulses are distorted in form.

Like many arrangements of the kind referred to, the arrangements according to the invention are only adapted to operate satisfactorily in response to a received train of impulses so long as the conditions are such that any necessary correction can be applied by causing the make to break ratio of repeated impulses to differ from the make to break ratio of the correspond- 21} ing distorted received impulses. It will hereinafter always be assumed that such conditions obtain. The arrangements are adapted both to lengthen the make periods at the expense of the break periods when necessary and to lengthen the break periods at the expense of the make periods when necessary.

According to the present invention, impulses received on an impulse-receivingrelay are repeated over an outgoing or apparatus-controlling circuit'by a combination of contacts of three different relays which combination comprises an impulse-repeating contact of the said impulsereceiving relay connected in series with the outgoing or controlling circuit, a primary auxiliary contact connected in series with the said impulse-repeating contact, and. a second auxiliary contact connected in parallel with the said'impulse-repeating contact, the said primary and second auxiliary contacts being respectively con-. 40 tacts of primary and secondary auxiliaryrelays which relays are controlled by the impulse receiving relay in such amanner that one of the auxiliary contacts operates to tend to'prevent the make periods of repeated impulses being short er than is permissible and that the other operates to tend to prevent the break periods of repeated impulses being shorter than is permissible. The apparatus-controlling circuit may be for example a circuit controlling a step-by-step switch or an impulse-repeating relay.

In the arrangements especially contemplated, the impulse-repeating contact is a make contact adapted to repeat break impulses, and the primary and secondary auxiliary contacts are re spectively a make contact of the primary auxiliary relay and a break contact of the secondary auxiliary relay; it being arranged that,

during impulsing the primary" auxiliary relay. directly controls the secondary auxiliary relay by a make contact and has its own control circuit 5 arranged so that an operating circuit is only completed for it whenthe condition arises that the impulse-receiving relay is operated and the secondary auxiliary relay is unoperated and so that when operated it only has its circuit opened when the condition arises that the impulse-receiving relay is unoperated and the secondary auxiliary relay is operated.

The drawings, comprising Figs. 1 and 2, when placed side by side show by way of example an outgoing relay set in which impulse correcting arrangements of this character are'incorporated.

In this outgoing junction relay set, A is the impulse-receiving relay and al is the impulse-repeating contact thereof. AA is the primary aux- 20 iliary relay with a make contact aa3 which serves as the primary auxiliary contact, and AB is the secondary auxiliary relay with a break contact ab l which serves as the secondary auxiliary contact. During impulsing, the primary 25 auxiliary relay AA directly controls the secondary auxiliary relay AB by a make contact (m4, and hasits own control circuit arranged so that an operating circuit is only completed for it when the condition arises that contact a2 is operated 0 andcontact abl is unoperated and so that when operated it only has its circuit opened when the condition arises that contact a2 is unoperated and contact ab2 is operated, The two conditions just mentioned are obviously A operated, AB un- .35 operated on the one hand and A unoperated, AB operated on the other hand. The normal cycle of operations of relays A, AA, and AB during the receipt of a train of impulses is A releases, AA releases, AB releases, A operates, AA operates, AB 40 operates.

In the arrangements just referred to asbeing especially contemplated, the minimum break period as regards repeated impulses is determined by the fact that the primary auxiliary re- '45 lay when released necessarily stays released with the primary auxiliary contact open until the secondary auxiliary relayhas also assumed the released condition, while the minimum make period as regards repeated impulses is determined 50 by the fact that the primary auxiliary relay when operated necessarily remains operated with the primary auxiliary contact closed until the secondary auxiliary relay has. also assumed the operated condition, opening of the impulse-repeat- 55 ing contact prior to this being ineffective as regards opening the outgoing or apparatus-controlling circuit owing to the presence of the secondary auxiliary contact. Thus, for example, if in the case of the outgoing junction relay set illustrated a received impulse-break intervening between make conditions which are of ample length is unduly short but causes relay A to be released long enough to release the primary auxiliary relay AA, then a break is repeated by contacts at and M3 which is of a length which depends on the sum of a number of time periods. These time periods are the time which elapses between the opening of the contacts of relay A and the release of relay AA (relays AA and AB will of course have operated during the ample make condition prior tothe beginning of the break), the time which elapsesbetween the opening of contact am and the release of the secondary auxiliary relay AB, and the time which elapses between the closure of contact abl and the re-operation of relay- AA. Again, if in the case of the outgoing junction relay'set illustrated a make period intervening between received breaks of ample length is unduly short but causes relay A to be operated long enough to operate the primary auxiliary relay AA, then a make is repeated by contacts M3 and (2114 which is of a length which depends on the time which elapses between the operation of the contacts oi relay AA and the operation of the secondary auxiliary relay AB, In other words, the minimum break period depends on the release lag of the primary auxiliary relay, the release lag of the secondary auxiliary relay, and the operating lag of the primary auxiliary relay, while the minimum make period depends on the operating lag of the secondary auxiliary relay.

It should be noted that with the arrangements which have been described as being especially contemplated, a momentary change of condition of the impulse-receiving relay due to switching operations at a preceding circuit might very well cause an impulse "break of minimum length to be given in so far as the outgoing or apparatuscontrolling circuit is concerned. To prevent this fact causing any difliculty the impulse-receiving relay is preferably of the type designed to hold operated on currents of very low value so that it does not respond to transient changes of current which are not due to the complete opening of its circuit. The use of such a relay tends to cause the operated periods of the relay to be prolonged at the expense of the released periods, but the effect of this on the repetition of impulses is neutralised by the operating lag of the primary auxiliary relay.

It has also been found desirable to arrange that the secondary auxiliary relay releases much more quickly than it operates, and that the amount of magnetisation which its magnetic circuit undergoes as a result of the comparatively long energisation of the operating winding prior to the commencement of an impulse train is limited by a resistance in series with this winding which resistance is short-circuited during the receipt of a train of impulses. In the outgoing junction relay set illustrated, the secondary auxiliary relay AB is caused to have the desired operating and releasing characteristics by providing it with a winding (II) in addition to its operating winding (I), this winding (II) being normally shunted by a circuit comprising a resistance YG in series with the break contact (1223 of the relay. By suitably choosing the resistance YG the required operating lag may readily be obtained. The operating winding (I) of the relay normally has both resistances YE and YF in series with it, but resistance YE is shortcircuited during the receipt of a train of impulses by the make contact c4 of a non-preoperated dialling relay C.

In the arrangements according to the invention, none of the relays provided for the purposes of impulse correction need be of the slowto-release type having a copper slug or sleeve on the-core.

The operation of the outgoing junction relay set shown in the accompanying drawings will now set is connected at the outgoing end of an interexchange junction in an automatic telephone system. The positive, negative, and private (P) wiresincoming to the relay set (on the left of the drawing) are multipled over the banks of a group of selectors. The positive and negative wires outgoing from the relay set (on the right of the drawing) are connected to the two wires of the inter-exchange junction. This junction serves for calls which are routed automatically at the distant end and which do not difier from one another as regards the fee to be charged.

'I'herelay set has a feeding bridge with impulse-receiving relay A and resistances YC and YD.on the incoming side and high-impedance relay I and polarised answering supervisory relay Don the outgoing side. The two condensers which link the incoming line wires to the outgoing line wires are designated QA and QB. The relayset is adapted to revert multi-metering impulses to preceding apparatus.

When the relay set is free with its apparatus at normal, it tests free to a searching selector by reason of the absence of earth on the incoming "P wire. a call by such a selector, relay A is operated in a'circuit which includes the impulsing loop which is controlling the setting up of the call. The circuit for relay A is earth, back contact dd2, winding (I) of relay A, the loop via the incoming speaking wires, winding (II) of relay A, back contacts on and ddl, resistances Y0 and YD, battery. The impulse-repeating contact al closes a point in a calling loop across the outgoing line wires, and contact a2 operates the primary auxiliary relay AA and the release relay B in circuits over contacts abl and (1112 respectively. Contacts-aal and (M2 close alternative circuits for relay AA, one circuit for this relay now being dependent only on relay A. Contact aa2 also closes a holding circuit for relay B. The primary auxiliary contact aa3 closes a further point in the calling loop across the outgoing line wires, and contact aal operates the secondary auxiliary relay'AB on its winding (I) in a circuit over resistances YE and YF. Contacts abl and abZ operate without immediate effect, contact 11123 opens the shunt across winding (II) of relay AB to render the relay more quick to release, and the secondary auxiliary contact (1124 operates without immediate effect. Contact bl connects earth over back contact dcl to the incoming P wire for engaging and holding purposes, and thus with contact b2 closes an operating circuit for relay HA including resistance YA. Contacts hal and m2 complete the calling loop over the outgoing line wires and contact ha3 closes an alternative circuit for relay HA. The calling loop includes the winding of relay I and the operating winding (I) of relay D, the latter winding I be described in detail, it being assumed that the 15 When the relay set is seized for '4 being shunted by a rectifier MBA. Relayl operates on the current which flows'round the loop from the distant end, but this current is not in the right direction to operaterelay D. Contact il closes a circuit over contacts brl and M for the polarising winding. (II) of relay D. The relay set is now in a condition to repeat trains of impulses to the automatic equipment at the distant end of the junction.

When the impulse-receiving relay A releases in response to the first implse of the first train to be repeated, contact (Ll opens the outgoing loop to initiate the repetition of the impulse and contact a2 releases the primary auxiliary relay AA. Back Contact aaZ closes a circuit for operating the dialling relay C on its two windings in series, the primary auxiliary contact aa3 opens to ensure that the repeated break has at least the minimum value as already explained, and co n-. tact aa l initiates the release of the secondary auxiliary relayAB. Contact cl closes a shortcircuit across relay I and winding (I) of relay D to provide a low-impedance loop for impulsing and relay I consequently releases, contact 02 closes an operating circuit for relay BB, contact 63 short-circuits the low-resistance winding (1) of relay C to render the relay slow to release, and contact c4 short-circuits resistance YE to modify the operating circuit of relay AB. It has been found desirable to arrange that contacts cl and c3 make at a late stage in the operation of relay C. The repeated break is terminated when relay AA is reoperated as the result of the closure of a circuit over contacts a2 and abl, i. e. is terminated as soon as relay AA is reoperated by the occurrence of a condition in which relay AB is unoperated and relay A is operated. The succeeding repeated make cannot be shorter than the operating lag of the secondary auxiliary relay AB, since it must at least persist until the secondary auxiliary contact abd again opens. That this is so is due to the fact that the primary auxiliary relay AA (and hence the primary auxiliary contact (1113) when operated remains operated, due to the circuit over contacts aaZ, 0.122, and cal, until the secondary auxiliary relay is operated. Relay C being slow to release holds during the receipt of the impulse train due to the intermittent energisation of its high-resistance winding (II). As usual the release relay B also holds during the receipt of the train. When relay BB operates, contact bb2 operates relay MD on its winding (I) in a circuit over contacts brl, b4 and dl. At the end of the impulse train, relay C releases. and relay I consequently reoperates, closing at contact 3 a circuit over contacts bbl and bb3 in which slow-to-release relay BB is held operated. It may be of use to record here that the relays operated at this stage are A, AA, AB, B, HA, BB, MD, and I.

Subsequent impulse trains are repeated in a similar manner, excepting of course that contact c2 merely holds relay BB operated during the repetition of a train instead of actually operating this relay.

If the called party is free, ringing tone current is received over the junction and passes via condensers QA and Q33 to the calling party. When the called party answers the call, contacts at the distant end of the junction effect a reversal of current in the line wires in the wellknown manner to eiiect the operation of the polarised answering supervisory relay D. Contact dl releases relay MD and closes a point in the circuitof winding (I) of relay DA, and con tact (12 operates relay DD.' Contacts doll and dd2 effect a reversal of current in the incoming line Wires to repeat the answering supervisory signal in case this should be necessary. It would be necessary for example in the case where the connection set up via the relay set does not originate at the exchange in which "the relay set is situated. Contact dd3 closes a holding circuit for relay BB. Relay A releases momentarily due to the changing over of contacts ddl and (1112, but relay MD is sufficiently slow to release to ensure that contact al is guarded by a circuit over contact mdl. Wires S and Z are cyclically and in sequence, by means of the continuously-operated interrupter contacts shown connected to them, connected to battery instead of earth. There is a substantial interval between the times when wires S and Z are connected to battery. The period for which wire Z is connected to battery starts before and covers the period during which battery pulses to effect multi-metering are applied to wire MP by the continuously-operated interrupter contact to which this wire is connected. The purposes served by wiresS and Z and the associated ap-v paratus are firstly to ensure that metering is not effected unless the answering supervisory relay D remains operated'for a reasonable time and secondly to disconnect the metering relays when metering has been effected. Assuming that relay D remains operated for the requisite time, relay DA operates on its Winding (I) in a circuit over wire S and contacts dbl, dl, b4 and hr],

and after the substantial interval already.re-'

ferred to relay DB is operated in the circuit battery, interrupter contact connected to wire Z, Wire Z,winding (I) of relay DB, contacts 126 and dal, holding winding (II) of relay DA, earth. During the interval relay DA is held on its holding winding (III) in a circuit which is dependent on contact ddd and which is hence indirectly dependent on relay D. Relay DB locks up for the duration of the call on its winding (II) in a circuit over resistance YB. Contact dbl opens a point in the circuit of winding (I) of relay DA to prevent subsequent re operation of this relay, and contact db; closes in the circuit of relay DC, so that this last-mentioned relay responds to those multi-metering pulses which are applied to wire MP during the period for which relay DA remains operated. Relay DA actually releases as soon as its winding (II) is de-energised when the battery is removed from Wire Z. Each time relay DC is impulsed, contact dcl booster battery potential to the incoming private wire in place of the usual holding earth. If the calling party is a subscriber belonging to the exchange in which the relay set is situated, the meter of this party is operated in the wellknown manner at each application. of booster battery. The booster battery circuit includes a heat coil HC and a resistance YM.

If at the end of the call the calling party clears first, then relay A releases and 'at contact at opens the loop across the outgoing junction wires, releasing relays I and D and initiating the release of the apparatus at the distant end of the junction. The opening of contact all releases relay AA. The opening of contact d2 and front contact all releases relay DD, and the closing of back contact dl operates relay MD. The falling back of contact aa2 initiates the slow release of relay B and operates relay C, and the opening of contact Ill/l4 releases relay AB. Conconnects relay BB. When relay B releases, contact 113 releases relay C, contact b4 initiates the slow re-. lease of relays MD and BB, and contact 125 releases relay DB. When relay MD releases, contact md3 removes the holding earth from the incoming P wire to initiate the release of the preceding apparatus and also releases relay HA. The outgoing junction relay set is then ready for use on another call.

If the called party clears before the calling party, relay D releases and brings about the release of relay DD and the rte-operation of relayv MD. Contacts ddl and (M2 cause the current in the incoming line wires to revert to its original direction to repeat the clearing signal in case this should be necessary. When the ca1l-- ing'party clears, the release of the connection proceeds in a manner similar to that described above.

If the called party is not free when called, then busy tone and lamp flash conditions are applied to the junction at the distant end thereof. The busy tone is heard by the calling party and relay I releases during lamp flash periods. On the first release of relay I, the opening of contact i3 releases relay BB. On the next operation of relay-I, relay ER is operated in a circuit over contacts mdZ, bbl, i3, D173, and a2. Contact 1W3 closes a short-circuit across contacts M3 and al to guard against subsequent release of relays A and AA during the repetition of the lamp flash signals,

and contact br l closes a circuit for the holding winding (II) of relay MD, an alarm lamp AL, and a common delayed alarm relay PA. On the second release of relay I, contact i2 closesa circuit over contact bri in which relay DD operates. With contact br2 operated, the operation of contacts ddl, and M2 results in the application of a lamp flash condition (i. e. battery on both wires) to the incoming line wires, so that the lamp flash signals received over the junction are repeated over the incoming wires in case this should be necessary. Relay ER is held during lamp flash periods in a circuit over contact dd3. Relay A releases during these periods, and at contact a2 brings about the release of relays AA, AB, and B, and the momentary re-operation of relay C, but these changes of condition of these relays are without efiect.

When the calling party clears, relay A cannot any longer be or remain operated during a tone period, and consequently relay BR releases, since the holding circuit for this relay via contacts a2, 22b3, i3, bbl and md2 previously closed at contact 112- during tone periods remains permanently open. The opening of contact br3 brings about the release of relay I and the apparatus at the distant end of the junction, and the opening of contact br l releases relay MD and extinguishes alarm lamp AL. Contact md3 on opening removes the holding earth from the incoming P wire to initiate the release of the preceding apparatus and also releases relay HA. The outgoing junction relay set is then ready for use on another call.

I claim:

1. An impulse repeater comprising a seriesparallel arrangement of three contacts in an outgoing circuit, and means controlled by electrical impulses received over an incoming circuit for operating said contacts thereby to transmit impulses over said outgoing circuit, one of the parallel contacts at times initiating each of the impulses transmitted over the outgoing circuit, the

tact c2 closes a temporary holding circuit for other. of the parallelfcontacts at other times initiating each of the impulses transmitted over the outgoing circuit, and the series contact terminating each impulse transmitted over the outgoing circuit.

. 2. Ina signalling system, an impulse receiving relay,'an impulse sending circuit including a contact of said relay, and two interdependent relays controlled by said impulse receiving relay each having a contact in said sending circuit, said two relays cooperating to prevent said sending circuit from being opened less than a predetermined interval of time or closed less than a predetermined interval of time during the sending of any impulse.

3. In, an electrical signalling system, an im-- pulse sending circuit, an impulsing contact connected in said circuit and operated by impulses of a certain character, and means including a contact connected in series with said impulsing contact and another contact connected in parallel with said impulsing contact operating to prevent said circuit from being opened less than a predetermined interval of time or closed less than a predetermined interval of time during the sending ofany impulse.

4. In an electrical-signalling system, a line, two contacts connected in series in said line, means controlled by impulses of a certain character for opening and closing one of said contacts in accordane with those impulses, means for opening the other of said contacts during the time said first contactis open and for closing said other contact after said first contact is closed, whereby the character of impulses transmitted over said line is determined by the opening of said one con tact and the closing of said other contact, and

timing means operating to prevent the closing of said other contact within a predetermined interval of time after the opening of said other contact.

5. In an electrical signalling system, a line, two contacts connected in series in said line, impulse operated means for opening one of said contacts responsive to the initiation of an impulse, for then opening the other of said contact in timed relationship to the opening of said one contact, for then closing said one contact responsive to the termination of said impulse, and at times for then closing said other contact in timed relationship to the closing of said one contact, and auxiliary means controlling said other contact effective at times to close said other contact in timed relationship to the opening of said other con-tact.

6. In a signalling system, a line, a line relay responsive to impulses transmitted over said line, a second relay normally operated responsive to each operation of the line relay and released responsive to each release of the line relay, an outgoing line having contacts of said two relays serially connected therein to control the transmission of impulses thereover, and means controlling both the minimum, time that said second relay shall have been operated before it can be released by said first relay and the minimum time that said second relay shall have been released before it can be operated by said first relay.

7. In a signalling system, an incoming line, an outgoing line, and three relays for controlling the transmission of impulses over said outgoing line, a first one of the relays energized and deenergized responsive to the corresponding energization and deenergization of the second one of the relays,

said second relay controlled conjointly by the first relay and the third relay whereby it is energized only when the deenergization of the first relay concurs with the energization of the third relay and is deenergized only when the energization of the first relay concurs with the deenergization of the third relay, said third relay being connected to the incoming line and energized thereover during one portion of each impulse and deenergized during another portion of each impulse.

8. In combination, a first relay and a second relay, both deenergized, a line, a line relay energized responsive to current flow over said line, a contact on said line relay thereupon closing an energizing circuit for said first relay, contacts on said first relay thereupon closing a holding circuit for said first relay and an energizing circuit for said second relay, said holding circuit including a normally closed contact on said second relay in parallel with said contact on the line relay, said normally closed contact insuring that said first relay remains energized at least during the energizing of said second relay, said first relay at times remaining energized thereafter over the contact on said line relay if the current continues to flow over said line after the energization of said second relay.

9. In combination, a first relay and a second relay, a circuit controlled by said first relay for energizing the second relay in timed relationship to every energization of the first relay and for deenergizing said second relay in timed relationship to every deenergization of said first relay, a line, a line relay responsive to impulses received over the line, and a circuit controlled conjointly by said line relay and said second relay for energizing said first relay only when an energization of said line relay concurs with a deenergization of said second relay and for deenergizing said first relay only when a deenergization of said line relay concurs with an energization of said second relay.

WILLIAM TYLER VOSPER. 

